# -*- coding: utf-8 -*-
from Tkinter import *

def frame(root, side):
	w = Frame(root)
	w.pack(side=side, expand=YES, fill=BOTH)
	return w

def button(root, side, text, command=None):
	w = Button(root, text=text, command=command)
	w.pack(side=side, expand=YES, fill=BOTH)
	return w

class Calculator(Frame):
	def __init__(self):
		Frame.__init__(self)
		self.pack(expand=YES, fill=BOTH)
		self.master.title('Calculadora')
		self.master.iconname('calcul1')

		display = StringVar()
		Entry(self, relief=SUNKEN, textvariable=display).pack(side=TOP, expand=YES, fill=BOTH)
		for key in ("123", "456", "789", "-0."):
			keyF = frame(self, TOP)
			for char in key:
				button(keyF, LEFT, char, lambda w=display, s='%s' % char: w.set(w.get()+s))
			opsF = frame(self, TOP)
		for char in "+-*/=":
			if char == '=':
				btn = button(opsF, LEFT, char)
				btn.bind('<ButtonRelease-1>', lambda e, s = self, w=display: s.calc(w), '+')
			else:
				btn = button(opsF, LEFT, char, lambda w=display, c=char: w.set(w.get()+' '+c+' '))
	
		clearF = frame(self, BOTTOM)
		button(clearF, LEFT, 'Clr', lambda w=display: w.set(''))
	def calc(self, display):
		try:
			display.set(`eval(display.get())`)
		except ValueError:
			display.set("ERROR")

if __name__ == '__main__':
	Calculator().mainloop()
